Where is the way to LED lighting

Ultra high brightness LED applications continue to expand, the first to enter the special lighting market, the industry is now fully engaged in the development of the general lighting market. The significance of LED for lighting has been widely known, however, the technical difficulties of epoxy encapsulation have not been overcome. Due to the continuous improvement of the input power of the LED chip, it is necessary to put forward higher requirements for the encapsulation technology of these power LED. Power LED packaging technology should meet the following requirements: first, the packaging structure to have a high light efficiency, and the two is to be as low as possible, so as to ensure the power of the photoelectric performance and reliability. In addition to the chip itself, the device packaging technology is also important. At present, the key technology of packaging technology is as follows: 1. Lamp type LED package structure of the traditional, usually with conductive or non-conductive adhesive chip in the small size of the reflection cup or stage, by wire device complete internal and external connection after epoxy resin encapsulation, the thermal resistance of up to 250 DEG /W to 300 DEG /W, power chip new if the LED package form of traditional style, because of poor heat will lead to the chip junction temperature rises rapidly and epoxy carbide yellow, resulting in accelerated depreciation until the device failure, even because of the rapid expansion of the thermal stress produced by open circuit failure. Therefore, for the power LED chip with large working current, the new packaging structure with low thermal resistance, good heat dissipation and low stress is the key technology of power LED devices. The low resistivity and high thermal conductivity materials bonded in chip chip; lower copper or aluminum heat sink, and the semi encapsulation structure, speed up the cooling; and even the design of two radiating device to reduce the thermal resistance of the device. In the interior of the device, filled with a high degree of transparency of flexible silicon modified epoxy material, in the temperature range can not withstand the sudden changes in temperature caused by the device open circuit, there will be no yellowing phenomenon. The thermal and thermal characteristics should be taken into account in order to obtain good thermal characteristics. Power LED is divided into two kinds of power LED and W power LED. The input power of the power LED is less than 1W (except for a few MW power LED); the input power of the W power LED is equal to or greater than 1W. Foreign power LED package, the earliest HP company launched the "piranha" package structure of LED in early 1990s, and in 1994 the introduction of improved "Snap LED", there are 2 kinds of current (respectively 70mA and 150mA, the input power is 0.3W), then OSRAM company launched the "Power TOP LED", after some companies have introduced various power LED package structure, the structure of power LED several times higher than the original input power LED bracket package, the thermal resistance of a fraction of W; power LED is the core part of future lighting, so the major companies in the world in great power, the Panasonic Corp launched in 2003 by the high-power white light LED 64 chip package. Nichia launched in 2003 is known as the most bright white LED in the world, the luminous flux of up to 600LM, the output beam is 1000lm, the power consumption of 30W, the maximum input power is 50W, with white LED light emitting efficiency of 33lm/W module exhibition. Multi chip combination of high-power LED, many companies in accordance with the actual market demand, and constantly develop a lot of new packaging structure of new products, the rapid development of its development. Domestic LED packaging products are more complete varieties, there are currently about 200 LED packaging manufacturers, packaging capacity of more than 20 billion / year, packaging supporting capacity is also very strong. However, many of the packaging plant for private enterprises, small scale. Good business: Taiwan UEC company (NL) metal bonding (Metal Bonding) characteristics of MB series high power LED package is replaced by Si GaAs substrate, good heat dissipation, and metal bonding layer of light reflecting layer, improve the light output. The thirteenth Research Institute of China Electronic Technology Group Corporation has carried out the research work on the power LED epoxy encapsulation technology, and developed the power LED products. The strength of the other LED package (with the exception of foreign investment enterprises), such as Foshan nationstar, Xiamen Hualian, early development of power LED development work and achieved good results, such as "piranha" and PLCC package structure of the product can be mass production, and has developed a high-power LED single package epoxy the samples of 1W chip. The development of domestic LED epoxy packaging technology is also facing difficulties. According to the introduction China epoxy resin industry association, for research and development of high-power LED packaging technology, the state has not yet officially supported investment, domestic research units rarely intervene, R & D investment package enterprise efforts (human and financial) is not enough, the formation of domestic packaging technology development strength of the weak situation, the technical level and package compared with foreign countries there is still a considerable gap.